1. Field of the Invention
The present invention relates to a substrate processing apparatus including a substrate storage container for accommodating a substrate, a method of manufacturing a semiconductor device, and a non-transitory computer-readable recording medium.
2. Description of the Related Art
Conventionally, a semiconductor manufacturing apparatus, which is a type of a substrate processing apparatus, performs a substrate processing process of processing a substrate (hereinafter referred to as a ‘wafer’) based on a recipe (process recipe) defining process conditions and sequences, as a process of manufacturing a device such as a dynamic random access memory (DRAM) or an integrated circuit (IC). In the substrate processing apparatus, a plurality of wafers are loaded into a process furnace in a state where the wafers are transferred to a substrate retainer (hereinafter referred to as a ‘boat’), and predetermined processing is performed on the wafers. In this case, since the start and end of the processing are waiting for in a state where the wafers are transferred to the boat in a transfer chamber installed below the process furnace, the wafers may be influenced by oxygen (O2) contained in the atmosphere before or after thermal processing is performed on the wafers. Accordingly, an N2 substitute mechanism is installed in the transfer chamber to manage the concentration of oxygen (O2) so as to be reduced to less than a predetermined level.
A substrate which is to be processed by the semiconductor manufacturing apparatus is accommodated in a front opening unified pod (FOUP) serving as a substrate storage container, and loaded into a support unit (hereinafter referred to as a ‘loading port”). When the FOUP is used, since a wafer is transferred in an airtight state, the degree of cleanliness of the wafer may be maintained even when particles or the like are present in an ambient atmosphere.
However, although the FOUP serving as a substrate storage container is an airtight container, the FOUP does not have a performance to completely block the flow of external air therein or therefrom. Thus, even if the FOUP is loaded in a device in an ideal state (e.g., a state where the concentration of O2 is a predetermined level or less), the concentration of the oxygen (O2) increases as time goes by until the FOUP is unloaded from the device. Therefore, in order to constantly maintain the concentration of the oxygen (O2) in the FOUP, purging needs to be performed using N2 gas while the FOUP is placed in the device. For example, a system of supplying an inert gas when a FOUP is placed on a cassette shelf is disposed in Patent Document 1.